Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Psychedelic Geometric Background No Black
Source GDJ
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile